HL 2 Biology

E.4a Neurotransmitter & Synapses

AA-CC: 331-2 • AA-SG: 138

Lesion Studies and Animal Experimentation

  • lesion: area in organ/tissue that suffered damage due to injury/disease (e.g. tumor)
    • changes personality and capacity for social interactions
    • e.g. Phineas Gage; damage to frontal lobes in his brain; personality changed
    • lesion experiments practiced on animals (vivisection)
      • remove parts of the skull, experiment on parts of brains

Functional Magnetic Resonance Imaging (fMRI)

  • MRI: useful technique to study internal structure of body & to find tumors/other conditions
  • fMRI: a specialized version of MRI; allows for observations in the brain activated by specific thought processes
    • active parts of the brain receive increased blood flow (fMRI scans this)
    • Process
      • patient placed in scanner
      • high-resolution scan of brain taken
      • low-resolution scans taken as stimulus is given to subject
      • scans show activated parts of the brain due to the stimulus

Pain and painkillers 

  • pain receptors in skin/body parts; detect stimuli
    • e.g. chemical substances in bee’s sting, heat from flame, puncturing skin
    • receptors nerve endings of sensory neurons (impulses to Central Nervous System)
    • as impulse reach sensory areas of cerebral cortex = experience pain
    • Natural painkillers (block pain):
      • Endorphins: oligopeptides secreted by pituitary gland
        • bind to receptors in synapses in pathways used in perception of pain
        • blocks synaptic transmission and prevents feeling pain


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